Researchers Seek to Reduce Bat Deaths from Wind Turbines

November 5, 2008

The Bats and Wind Energy Cooperative (BWEC) announced in mid-October
that it has begun testing a procedure to stop wind turbines during low-wind conditions to avoid killing bats. Bat deaths from wind turbines are
a relatively recently discovered phenomenon, and although they are not
fully understood, recent studies have suggested that most bat deaths
occur on low-wind nights when the turbines are producing low amounts of
power, but may be rotating near their maximum speed. Based on that
finding, Iberdrola Renewables has agreed to shut down the turbines at
its Casselman Wind Power Project in Pennsylvania during low-wind
conditions. The experiment will provide information on how the new
operating procedure will effect both bat deaths and power production at
the 34.5-megawatt facility, which is located southeast of Pittsburgh. The
BWEC is a unique alliance of Bat Conservation International, the
American Wind Energy Association (AWEA), the U.S. Fish and Wildlife
Service (FWS), and DOE's National Renewable Energy Laboratory. See the
BWEC press release
(PDF 90 KB) and
Web site.
Download
Adobe Reader.

Iberdrola Renewables isn't just helping out the BWEC experiment; the
company has also committed to responsibly developing wind power while
addressing wildlife concerns. Last week, Iberdrola released a company-wide Avian and Bat Protection Plan, modeled on a similar plan to
address the impacts of power lines on birds. Preparing in consultation
with the FWS, the plan establishes a process for contact with
government agencies and non-governmental organizations early in the
site assessment stage of new wind power projects. It also includes
policies for pre- and post-construction monitoring and other measures
to reduce and mitigate bird and bat deaths. See the Iberdrola
Renewables
press release
and plan (PDF 2.9 MB).

While bat deaths remain poorly understood, a recent study by the
University of Calgary suggests that it's not an actual impact with wind
blades that kills bats, but rather the effects of the pressure drop
caused by the moving blades. Large numbers of migratory bats are being
killed by some of the turbines in southern Alberta's wind facilities,
and a study of the dead bats at one of those sites found that the bats
suffered severe injuries to their respiratory systems consistent with a
sudden drop in air pressure, a condition known as barotrauma. While
only half of the dead bats showed signs of being struck by wind turbine
blades, 90% had injuries consistent with barotrauma. The study was
published in the August 26 online edition of Current Biology.
See the University of Calgary press release.